A thermoelectric conversion element is an electronic element which can carry out interconversion between heat and electricity, known as the Seebeck effect or the Peltier effect. The Seebeck effect is an effect of converting heat energy into electric energy. The Seebeck effect is a phenomenon in which an electromotive force is produced in a case where a temperature difference is caused between both ends of a thermoelectric conversion material. The electromotive force depends on the characteristics of the thermoelectric conversion material. In recent years, thermoelectric generation using the effect has been actively developed.
In contrast, the Peltier effect is an effect of converting electric energy into heat energy. The Peltier effect is a phenomenon in which a temperature difference is caused between both ends of a thermoelectric conversion material in a case where electrodes and the like are formed at both ends of the thermoelectric conversion material, and a potential difference is caused between the electrodes. An element having such an effect is particularly called a Peltier element, and is used for cooling or temperature control of precision instruments, compact refrigerators, and the like (for example, see Patent Document 1).
In recent years, attention has been paid to a technique of effectively utilizing waste heat by using a thermoelectric generation module exploiting the Seebeck effect. For example, a technique has been suggested in which a thermoelectric generation module using the Seebeck element is mounted on a discharge pipe for an exhaust gas from an automobile engine or on a wall surface of a pipe through which a high-temperature fluid flows in a factory, a plant, and the like while a thermoelectric conversion member such as a heatsink is mounted on the other surface of the thermoelectric generation module for heat dissipation so as to use the heat of the pipe by converting it into electric power.
As the aforementioned thermoelectric generation device, for example, a device is known which includes cylindrical thermoelectric generation devices each having a plurality of built-in modularized thermoelectric conversion elements, in which the thermoelectric generation devices are vertically disposed in one path through which an exhaust gas or cooling water passes, another path through which cooling water or an exhaust gas passes is formed on the inside of each of the thermoelectric generation devices, and thermoelectric generation is carried out by exploiting the temperature difference between the inside and the outside of the plurality of cylindrical thermoelectric generation units lining up in parallel (for example, see Patent Document 2).
Furthermore, a thermoelectric conversion system is known which includes cylindrical thermoelectric generation devices each having a plurality of built-in modularized thermoelectric conversion elements, in which a fin is mounted on the thermoelectric generation devices so as to make cartridges, and the plurality of thermoelectric generation devices made into cartridges are arranged in parallel (for example, see Patent Document 3).